Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have examined 35 epidermal tumors induced in mice of four different strains by chronic exposure to ultraviolet B radiation for the presence of aberrations in the p53 tumor suppressor gene. Polymerase chain reaction products from p53 exons 5 to 8 were screened by single-strand conformation polymorphism analysis and sequencing. Base substitutions were found in seven tumors (20%). All mutations occurred at dipyrimidine sequences; most frequent were C-->T single base and CC-->TT tandem transitions suggesting the involvement of UV radiation in the genesis of the mutations. Three base substitutions were located at codon 148, and all dipyrimidine-derived mutations occurred at sites where the sequence is present in the nontranscribed DNA strand, indicating some site and strand specificity of the ultraviolet B-induced p53 mutations.
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PMID:Carcinogen-specific mutational pattern in the p53 gene in ultraviolet B radiation-induced squamous cell carcinomas of mouse skin. 142 88

Cell cycle checkpoints can enhance cell survival and limit mutagenic events following DNA damage. Primary murine fibroblasts became deficient in a G1 checkpoint activated by ionizing radiation (IR) when both wild-type p53 alleles were disrupted. In addition, cells from patients with the radiosensitive, cancer-prone disease ataxia-telangiectasia (AT) lacked the IR-induced increase in p53 protein levels seen in normal cells. Finally, IR induction of the human GADD45 gene, an induction that is also defective in AT cells, was dependent on wild-type p53 function. Wild-type but not mutant p53 bound strongly to a conserved element in the GADD45 gene, and a p53-containing nuclear factor, which bound this element, was detected in extracts from irradiated cells. Thus, we identified three participants (AT gene(s), p53, and GADD45) in a signal transduction pathway that controls cell cycle arrest following DNA damage; abnormalities in this pathway probably contribute to tumor development.
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PMID:A mammalian cell cycle checkpoint pathway utilizing p53 and GADD45 is defective in ataxia-telangiectasia. 142 16

The DNA binding activity of p53 is required for its tumor suppressor function; we show here that this activity is cryptic but can be activated by cellular factors acting on a C-terminal regulatory domain of p53. A gel mobility shift assay demonstrated that recombinant wild-type human p53 binds DNA sequence specifically only weakly, but a monoclonal antibody binding near the C terminus activated the cryptic DNA binding activity stoichiometrically. p53 DNA binding could be activated by a C-terminal deletion of p53, mild proteolysis of full-length p53, E. coli dnaK (which disrupts protein-protein complexes), or casein kinase II (and coincident phosphorylation of a C-terminal site on p53). Activation of p53 DNA binding may be critical in regulation of its ability to arrest cell growth and thus its tumor suppressor function.
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PMID:Regulation of the specific DNA binding function of p53. 142 35

Using the polymerase chain reaction and single-strand conformation polymorphism analysis, p53 gene mutations were examined in 24 cases of ovarian tumor including 14 ovarian carcinomas and 2 borderline cases of common epithelial type, 7 germ cell tumors, and one stromal tumor. Abnormal bands indicating mutations were detected in 12 (50%) of the cases examined, being present most frequently in common "epithelial" ovarian carcinoma (71%, 10/14). One case each of squamous cell carcinoma originating in a dermoid cyst and anaplastic dysgerminoma were positive for mutation. Direct sequencing confirmed 12 mutations and revealed G-->A and G-->C nucleotide changes in 5 and 3 cases (42% and 25%), respectively. The mutation was localized at the CpG site of the gene in 3 cases. Immunohistochemical examination of p53 protein in 21 cases and DNA flow-cytometrical analysis in 17 cases were also performed. Nuclear accumulation of the p53 protein and DNA aneuploidy pattern were detected in 11 (52%) and 9 (53%) cases, respectively. These were significantly correlated with p53 gene mutation (P < 0.01 and P < 0.05, respectively; Fisher's exact test). Neither mutation of the p53 gene, nuclear accumulation of p53 protein nor DNA aneuploidy was detected in borderline cases of common "epithelial" type, typical dysgerminoma and immature teratoma. These results suggest that p53 gene mutation, nuclear accumulation of the protein and the DNA aneuploidy pattern are events occurring almost simultaneously in the progression of ovarian tumors, and that p53 abnormalities seem to be correlated with a high grade of malignancy.
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PMID:High incidence of p53 gene mutation in human ovarian cancer and its association with nuclear accumulation of p53 protein and tumor DNA aneuploidy. 142 9

By blot hybridization we found that DNA fragments of eukaryotic 18 and 28S rRNAs bind specifically with mRNA. In these experiments the in vitro transcribed mRNA of mouse gene p53 was used. In addition we found that both 18 and 28S rRNAs were able to form intermolecular complexes with mRNAs of several genes 18S rRNA-mRNA; 28S rRNA-mRNA, but fail to bind the antisense RNAs of the same genes. The experimental data allow to suppose that 18S and 28S rRNAs carry several fragments that are complementary to some fragments in the mRNA sequences.
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PMID:[Interaction of mRNA of the p53 protein gene with ribosomal RNA]. 143 81

Mutations in the p53 gene are most frequent in cancer. Many p53 mutants possess transforming activity in vitro. In cells transformed by such mutants, the mutant protein is oligomerized with endogenous cell p53. To determine the relevance of oligomerization for transformation, miniproteins containing C-terminal portions of p53 were generated. These miniproteins, although carrying no point mutation, transformed at least as efficiently as full-length mutant p53. Transforming activity was coupled with the ability to oligomerize with wild-type p53, as well as with the ability to abrogate sequence-specific DNA binding by coexpressed wild-type p53. These findings suggest that p53-mediated transformation may operate through a dominant negative mechanism, involving the generation of DNA binding-incompetent oligomers.
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PMID:Identification of a minimal transforming domain of p53: negative dominance through abrogation of sequence-specific DNA binding. 144 88

This study was undertaken to analyze the effect of wild-type p53 transfection on the growth potential of a human lung cancer cell line Hut292DM expressing endogenous wild-type p53. Transfection efficiencies obtained with either the wild-type or a mutant p53 complementary DNA revealed a significant decrease in the number of colonies obtained with the wild-type p53 as compared to the mutant p53 complementary DNA (27%) or control vector DNA only (20%), suggesting that wild-type p53 inhibited the growth of Hut292DM cells. A series of wild-type and mutant p53 transfection clones were then analyzed for the presence and expression of the exogenous p53 gene. Polymerase chain reaction amplification revealed that 98% of mutant p53 transfection clones analyzed contained the exogenous p53 gene as opposed to 47% for wild-type p53 clones. The majority of mutant p53 clones expressed high levels of exogenous p53 mRNA and protein as analyzed by Northern and Western blots, respectively. In contrast, all wild-type p53 clones analyzed failed to express exogenous p53 mRNA transcript or protein of a normal size. Aberrant-size p53 mRNA was detected in two wild-type p53 clones (X833.W2 and W18), and Western blot analysis revealed that these clones expressed truncated p53 proteins (M(r) 45,000 and 33,000 respectively). No difference in proliferation rates in vitro or in tumorigenic potential in nude mice were observed between mutant p53 clones or control cell lines. In contrast, a wild-type p53 clone (X833.W2) exhibited a significantly reduced tumorigenic potential in nude mice, whereas its in vitro proliferation rate was comparable to parental Hut292DM cells. The data indicate that exogenous expression of wild-type p53 is incompatible with Hut292DM lung cancer cell proliferation in vitro and suggest that p53-mediated growth control in vitro and in vivo may be dissociated and exerted by separate domains of the p53 protein.
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PMID:Growth suppression mediated by transfection of p53 in Hut292DM human lung cancer cells expressing endogenous wild-type p53 protein. 145 87

Germ line p53 mutations represent a genetic predisposition for cancer development. At the present time, their detection requires extensive work and their functional significance must be documented. Therefore, we have designed a simple biological assay which detects functionally significant germ line p53 mutations. This assay is based on the cloning of the patient's p53 complementary DNA into a eukaryotic expression vector followed by the cotransfection into human cells of the recombinant vector with a reporter plasmid for the transcriptional activity of p53. This assay potentially offers a powerful method to screen fibroblasts or lymphocytes from patients for germ line mutations which inactivate the p53 tumor suppressor gene.
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PMID:A functional screen for germ line p53 mutations based on transcriptional activation. 145 90

The frequencies of mutations in the p53 tumor-suppressor gene and ras proto-oncogenes were investigated systematically in surgically resected oral squamous-cell carcinomas (SCCs) using single-strand conformation polymorphism (SSCP) and/or dot-blot hybridization analysis of DNA fragments which had been amplified by the polymerase chain reaction (PCR). p53 gene mutations, within the region of exons 5 to 8, were detected in 17 out of 27 (63%) tumor specimens. The role of p53 mutations in cell-line establishment was investigated. p53 gene mutations were detected in 5 out of 6 tissue samples from which cell lines were established and in 4 out of 5 specimens from which cell lines could not be established, suggesting that the presence of p53 gene mutations is not by itself sufficient for cell-line establishment. Tumor samples were also analyzed for point mutational activation of the ras proto-oncogenes. One out of 30 (3%) tumors showed an activating point mutation in codon 12 of H-ras, this being consistent with reports from Europe and USA but not with any from India. Compared to frequencies of the other genetic changes so far reported for oral SCC, the p53 mutations have been observed most often to undergo genetic change. p53 gene mutation is thus intimately involved in the genesis of oral SCC and consequently should be useful as a marker for the diagnosis of this neoplasm.
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PMID:The p53 tumor-suppressor gene and ras oncogene mutations in oral squamous-cell carcinoma. 145 26

There are many reports of cell lines being established from human oral squamous-cell carcinomas but apparently none of cell lines from dysplastic or "pre-malignant" oral mucosa. We describe here the isolation and characterization of a cell line, DOK (dysplastic oral keratinocyte), from a piece of dorsal tongue showing epithelial dysplasia. The tissue was obtained from a 57-year-old man who was a heavy smoker prior to the appearance of a white patch on his tongue. Eleven years later a squamous-cell carcinoma developed at the site and was excised. Subsequently the remaining dysplasia was removed, and it was from a piece of this that the primary cell cultures which eventually gave rise to DOK were initiated. The DOK line has been single-cell cloned and is apparently immortal. It grows in the absence of 3T3 feeder cells, is anchorage-dependent for growth and is non-tumorigenic in nude mice. The keratin profile of the cells shows a striking similarity to that of the original tongue dysplasia. The karyotype of DOK is aneuploid and complex. By PCR and oligonucleotide hybridization on dot blots, codons 12, 13 and 61 of Ha-ras, Ki-ras and N-ras in DNA extracted from DOK cells were shown to be normal. Immunohistochemistry showed no abnormal, i.e., elevated expression of the onco-suppressor protein p53. Because of its origin and partially transformed phenotype, DOK presents an opportunity to study whether specific carcinogens associated with tobacco and areca nut can cause malignant transformation of oral keratinocytes in vitro.
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PMID:DOK, a cell line established from human dysplastic oral mucosa, shows a partially transformed non-malignant phenotype. 145 32


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